package com.mrx.java8.stream.parallel;

import java.util.concurrent.RecursiveTask;

/**
 * @create 2018-12-01 17:15
 */
public class ForkJoinCalculate extends RecursiveTask<Long> {
    private static final long serialVersionUID = 8664599239343064301L;

    private long start;
    private long end;

    private static final long THRESHOD = 10000;

    public ForkJoinCalculate(long start, long end) {
        this.start = start;
        this.end = end;
    }

    @Override
    protected Long compute() {
        long length = end - start;
        if(length<=THRESHOD){
            long sum = 0;
            for (long i=start;i<=end;i++){
                sum += i;
            }
            return sum;
        }else {
            long middle = (start+end)/2;
            ForkJoinCalculate left = new ForkJoinCalculate(start,middle);
            left.fork(); // 拆分子任务，同时压入线程队列

            ForkJoinCalculate right = new ForkJoinCalculate(middle+1,end);
            right.fork();

            return left.join()+right.join();
        }
    }
}
